 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui;

 /**
  * A page service tracks the page and perspective lifecycle events
  * within a workbench window.
  * <p>
  * This interface is not intended to be implemented by clients.
  * </p>
  *
  * @see IWorkbenchWindow
  * @see IPageListener
  * @see IPerspectiveListener
  */
 public interface IPageService {
     /**
      * Adds the given listener for page lifecycle events.
      * Has no effect if an identical listener is already registered.
      *
      * @param listener a page listener
      */
     public void addPageListener(IPageListener listener);

     /**
      * Adds the given listener for a page's perspective lifecycle events.
      * Has no effect if an identical listener is already registered.
      *
      * @param listener a perspective listener
      */
     public void addPerspectiveListener(IPerspectiveListener listener);

     /*
      * Returns the active page.
      *
      * @return the active page, or <code>null</code> if no page is currently active
      */
     public IWorkbenchPage getActivePage();

     /**
      * Removes the given page listener.
      * Has no affect if an identical listener is not registered.
      *
      * @param listener a page listener
      */
     public void removePageListener(IPageListener listener);

     /**
      * Removes the given page's perspective listener.
      * Has no affect if an identical listener is not registered.
      *
      * @param listener a perspective listener
      */
     public void removePerspectiveListener(IPerspectiveListener listener);
 }

